A linear motion bearing is a bearing to be used for guiding a linear motion part of a table or a positioning table of a machine tool, for example.
In such a bearing, there are defined between the bearing assembly and the rail base axial gaps, that is, gaps between opposite end surfaces of the bearing assembly and the rail base and transverse gaps, that is, gaps between side surfaces of the rail base and the bearing assembly. To prevent entry of a foreign matter such as dust from the gaps and also prevent leakage of a lubricant from the bearing assembly, a sealing structure is normally provided to the bearing assembly.
Such a sealing structure is known from Japanese Utility Model Publication No. 43136/1987. The known sealing structure is shown in FIGS. 5 to 7, in which a sealing structure 50 is constructed of a pair of side plates 51, a pair of connecting portions 52 and rubber 53 is fixed to the side plates 51 and connecting portions 52. The sealing structure 50 having this construction is mounted to the bearing assembly to thereby prevent the entry of a foreign matter and the leakage of a lubricant.
However, the sealing structure 50 is manufactured by first pressing a planar plate, then putting the rubber by baking to the plate, and finally bending the plate with the rubber. Thus, a rubber baking step is included in a machining operation to render a total step complicated and increase a manufacturing cost.
Further, when the sealing structure 50 is fixed to the bearing assembly, a fixing position of the sealing structure 50 must be adjusted so as to suitably fit a sealing lip to the rail base.